1. Field of the Invention
The present invention relates to a method for manufacturing an electronic component and an apparatus for manufacturing the same, particularly to a method for manufacturing an electronic component that requires a paste such as a conductive paste to be coated on a part of the side faces of a component body provided with an electronic component, and to an apparatus for manufacturing the same.
2. Description of the Related Art
FIG. 16 shows a perspective view of the appearance of an electronic component 1 in concern with the present invention. The electronic component having three or more terminals such as, for example, a three-terminal capacitor, a capacitor array, a LC composite EMI filter and a capacitor network assumes an appearance as shown in FIG. 16.
The electronic component 1 comprises, for example, a rectangular column shaped electronic part 2. The terminals provided on this electronic component 1 include end face electrodes 5 and 6 formed on the end faces 3 and 4, respectively, in opposed relation with each other, while side face electrodes 9 and 10 are formed with a predetermined width on the other side faces 7 and 8, respectively, in opposed relation with each other.
Not only the end face electrodes 5 and 6 are formed on the end faces 3 and 4, respectively, but also adjoining face extension parts 13 and 14 are extended onto a part of the side faces 7 and 8 adjoining the end faces 3 and 4, besides extending up to a part of the other pair of the side faces 11 and 12. The side face electrodes 9 and 10 not only extend onto the side faces 7 and 8, respectively, but also have adjoining face extension parts 15 and 16 extending up to a part of the side faces II and 12 adjoining the side face electrodes 9 and 10.
These adjoining face extension parts 13 to 16 serve for improving soldering property to the wiring board (not shown) when the electronic part 1 is mounted thereon.
What is concerned with the present invention is a technology particularly for forming the side face electrodes 9 and 10.
An apparatus 17 is shown in FIG. 17 in order to form the side face electrodes 9 and 10. The apparatus 17 is provided-with a slit plate 18 made of a metal, and a plurality of slits 19 having a width corresponding to the width of the side face electrodes 9 and 10 are provided on the slit plate 18. The slit plate 18 is placed so as to shut the upper opening of a paste vessel 21 accommodating a conductive paste 20. A cylinder 22 is provided to be connected with the space in the paste vessel 21, and a piston is provided in the cylinder 22.
The component body 2 is firstly disposed so that its one side face 7 contacts the slit plate 18. The conductive paste 20 is fed through the slit 19 by allowing the piston 23 to move along the direction of an arrow 24 so that the paste swells on the upper face of the slit plate 18, while the side face of the component body is in contact with the slit plate, thereby the conductive paste 20 is coated on a part of the side face 7 of the component body 2. The conductive paste is also coated on a part of the side faces 11 and 12 adjoining the side face 7 of the component body 2.
The same procedure is also applied to the other side face 8 of the component body 2.
Subsequently, the conductive paste 20 coated on the component body 2 is baked, and the side face electrodes 9 and 10 comprising the adjoining face extension parts 15 and 16, respectively, as shown in FIG. 16 are formed using the conductive paste 20.
An apparatus 25 is also shown in FIG. 18 in place of the foregoing apparatus 17.
The apparatus 25 has a coating plate 26 comprising an elastic material capable of elastic deformation such as a rubber. A plurality of grooves 27 having a width corresponding to the width of the side face electrode 9 or 10 are provided on the coating plate 26, and the grooves 27 are filled with the conductive paste 28.
The component body 2 is compressed against the coating plate 26 while one side face 7 comes into contact with the coating plate 26, thereby the component body 2 allows the coating plate 26 to deform along the direction of thickness. As a result, the conductive paste 28 in the groove 27 is coated on a part of the side face 7 of the component body 2 with a predetermined width, as well as on a part of the adjoining side faces 11 and 12 by allowing a part of the conductive paste 28 to swell onto the upper face of the coating plate 26.
The same step is also applied on the other side face 8 of the component body 2.
The conductive paste 28 is baked thereafter by the same way as in the case using the apparatus 17 shown in FIG. 17. The side face electrodes 9 and 10 having the adjoining face extension parts 15 and 16 as shown in FIG. 16 are formed using the conductive paste 28.
However, the following problems arise when the apparatus 17 shown in FIG. 17 is used.
As hitherto described, a plurality of slits 19 are provided on the slit plate 18, and the component bodies 2 corresponding to respective slits 19 are disposed. The plural component bodies 2 are held by being arranged on a plane using an appropriate holder (not shown), and are positioned so as to correspond to respective slits 19.
However, it happens that some of the components bodies 2 may be accidentally deficient at specified portions of the holder, when a plurality of the components bodies 2 are held with the holder, whereby no component bodies 2 are present on the specified portions of the slit 19 remaining the portion of the slit to be open. Consequently, since the pressure applied from the piston 23 is readily released through the open portion of the slit 19, the amount of the coated conductive paste 20 on the component body 2, particularly the coating level of the conductive paste 20 to serve as the adjoining face elongation parts 15 and 16, tends to be irregular. This irregularity may well arise not only among the component bodies 2 that are simultaneously treated, but also among the component bodies 2 that are treated in each repeating process.
For solving the problems as described above, it is contemplated to coat the conductive paste 20 on the component body 2 after forming a gap between the component body 2 and the slit plate 18. However, it is difficult to form the side face electrode 9 or 10 with a uniform width., because the width of the side face electrode 9 or 10 becomes wider to an extent not to be negligible than the width of the slit 19, besides making the width of the electrodes wider at the center of the side face. Accordingly, such solving means are inappropriate when the side face electrode 9 or 10 should be formed with finer width, or when a plurality of the side face electrodes having a narrow pitch are desired to be formed on specified side faces (not shown).
For solving the foregoing problems, it can be also contemplated that the slit 19 is so designed as to have a narrower width than the width required for the side face electrode 9 or 10. However, the conductive paste 20 turns out to be left in the slit thus requiring the slit as well as the paste vessel 21 to be frequently cleaned, arising a problem of decreased work efficiency.
The following problems arise, on the other hand, when the apparatus 25 as shown in FIG. 18 is used.
The elastic material such as a rubber constituting the coating plate 26 may be swelled by the effect of organic solvents contained in the conductive paste 28. The organic solvents are pervaded into the elastic material with time lapsing. Such swelling and pervasion not only shortens the service life of the coating plate 26, but also accidentally happens to deform the coating plate 26, thereby the positional accuracy for coating the conductive paste 28 onto the component body 2 is decreased with time.
Frequent cleaning of the coating plate 26 is also required, since the conductive paste is liable to be remained in the groove 27 because the conductive paste 28 filled in the groove 27 of the coating plate 26 is dried up, or the organic solvent contained in the conductive paste infiltrates into the coating plate 26, also arising a problem that the work efficiency is decreased.